This invention relates in general to electrostatographic reproduction machines, and more particularly to a noise-free silencer assembly for reducing self-vibration noises, and screeching noises between a cleaning blade and the imaging member of an electrostatographic reproduction machine.
Electrostatographic imaging members are well known in the art. The imaging members may be in the form of various configurations such as a flexible web type belt or cylindrical drum. The drums comprise a hollow cylindrical substrate and at least one electrostatographic coating. These drums are usually supported by a hub held in place at the end of each drum. The hub usually includes a flange that extends into the interior of the drum and usually retained in place by an adhesive. An axle shaft through a hole in the center of each hub supports the hub and drum assembly.
Electrostatographic imaging members as such may be electrostatographic or electrographic members. It is well known that electrostatographic members comprise at least one photosensitive imaging layer and are imaged with the aid of activating radiation in image configuration whereas electrographic imaging members comprise at least one dielectric layer upon which an electrostatic latent image is formed directly on the imaging surface by shaped electrodes, ion streams, styli and the like. A typical electrostatographic imaging process cycle involves forming an electrostatic latent image on the imaging surface, developing the electrostatic latent image to form a toner image, transferring the toner image to a receiving member and cleaning the imaging surface. Cleaning of the imaging surface of electrostatographic imaging members is often accomplished with a doctor type resilient cleaning blade that is rubbed against the imaging surface of the imaging members.
When electrostatographic imaging members are cleaned by doctor type cleaning blades rubbing against the imaging surface to remove residual toner particles remaining on the imaging surface after toner image transfer to a receiving member, a high pitched ringing, squealing, squeaking, or howling sound can be created which is so intense that it is intolerable for machine operators. This is especially noted in drum type imaging members comprising a hollow cylindrical substrate. The sound apparently is caused by a xe2x80x9cstick-slipxe2x80x9d cycling phenomenon during which the cleaning blade initially xe2x80x9csticksxe2x80x9d to the imaging surface and is carried in a downstream direction by the moving imaging surface to a point where resilience of the imaging blade forces the tucked blade to slip and slide back upstream where it again sticks to the photoreceptor and is carried downstream with the imaging surface until blade resilience again causes the blade to flip back to its original position.
The upstream flipping motion kicks residual toner particles forward. The stick-slip phenomenon is somewhat analogous to the use of a push broom for cleaning floors where the push broom is most effective for cleaning when it is pushed a short distance and then tapped on the floor with the cycle being repeated again and again. This stick-slip phenomenon is important for effective removal of residual untransferred toner particles from an imaging surface and for prevention of undesirable toner film or toner comets from forming on the imaging surface during cleaning.
An adhesive relationship between the cleaning blade and the imaging member surface appears to contribute to the creation of the ringing, squealing, squeaking, or howling sound. More specifically, the stick-slip effect occurs where there is a strong adhesive interaction between the cleaning blade and the imaging surface. The ringing, squealing, squeaking, or howling sound appears to be caused by resonant vibration of the drum induced by the stick-slip phenomenon. Other factors contributing to creation of the ringing, squealing, squeaking, or howling sound may include factors such as the construction of the imaging member, the blade contacting the imaging member, the type of blade holder construction, and the like. For example, a flimsy blade holder can contribute to the howling effect. Moreover, a thinner, shorter, stubbier cleaning blade tends to contribute the howling effect. Thin imaging member drums can also lead to the howling effect.
The stick-slip phenomenon also depends on the lubricating effect of toner and/or carrier materials utilized. Moreover, ambient temperatures can contribute to the creation of howling. It appears that resonance is initiated at the point of contact between the cleaning blade and the imaging member. The creation of the squealing or howling sound might be analogous to rubbing a fingertip around the edge of a wine glass. The squealing or howling noise phenomenon is especially noticeable for cylindrical photoreceptors having a hollow metal or plastic drum shaped substrate. Generally, where the imaging member is the cause of a howling sound, it will emit a ringing sound when tapped.
These sounds cannot be tolerated in a office environment. To overcome this drawback, various devices have been developed which can be inserted inside the hollow drum to dampen the drum and diminish or eliminate all irritating sounds emitted during imaging operation. Some of these devices include, for example, porous members which are compressed when inserted inside a hollow photoreceptor drum to perform a sound deadening function while pressing against the inner surface of the drum. Examples of this type of sound dampener is described, in U.S. Pat. No. 5,722,016, Japanese Patent Publication 63060481, published Mar. 16, 1998 and Japanese Patent Publication 63271388, published Nov. 9, 1998.
Another such device for preventing undesirable sounds in a drum photoreceptor includes a control member having a xe2x80x9cCxe2x80x9d cross-section. This type of device is described, for example, in Japanese Patent Publication 02118684, published May 2, 1990. This device is difficult to compress and slide into a hollow drum unless the control member is very thin. A very thin control member may not have sufficient mass to dampen any squeaking sound. However, thicker silencer members having a xe2x80x9cCxe2x80x9d shaped cross-section may be utilized if modified to form a hinge of thinner material extending axially along the length of the xe2x80x9cCxe2x80x9d shaped member. The hinge of thinner material is preferably located opposite the gap of the xe2x80x9cCxe2x80x9d shaped member. This hinge allows a relatively thick silencer to be more easily squeezed so that the exposed ends at the longitudinal gap come together to form a silencer having a smaller cross-section thereby allowing the silencer to be inserted into the hollow drum. This arrangement also facilitates removal of the silencer from the drum for recycling.
Conventionally, the xe2x80x9cCxe2x80x9d shaped cross-section silencers each consist of a tube having a straight external hinge feature and an opposing slot that are both cut into the tube and aligned parallel to the tube axis. Unfortunately, it has been found that the parallel alignment of the hinge feature and slot in these silencers undesirable contribute to self-vibration noises or vibrational chattering noises coming from the silencer tubes themselves.
It has been found that there is a significant risk having two or more conventional silencers aligned within the photoreceptor drum of a machine, in such way that their parallel slots and hinge recesses are lined up with the axis of the drum and with each other. In such a case, such an alignment is likely to cause photoreceptor drum distortion because there is a significant radial outward force exerted by the silencers against the thin wall of the photoreceptor drum.
Thus, there is a need for a noise-free silencer assembly that reduces self-vibration noises, and screeching noises between a cleaning blade and the imaging member of an electrostatographic reproduction machine.
In accordance with the present invention, there is provided a noise-free silencer assembly for reducing self-vibration noises, and screeching noises between a cleaning blade and the imaging member of an electrostatographic reproduction machine. The noise-free silencer assembly comprises a C-shaped cross-section elongate member having (a) a longitudinal axis, a wall defining an interior cavity for containing at least a partially compressed high density polymeric open cell foam, (b) a slot formed in the wall extending generally longitudinally and at an angle to the longitudinal axis of the C-shaped cross-section member, and (c) a hinge recess also formed in the wall extending generally longitudinally, for reducing self-vibration noises and screeching noises between a cleaning blade and an imaging member of an electrostatographic reproduction machine.
In accordance with the present invention, there is provided a noise-free silencer assembly for reducing self-vibration noises, and screeching noises between a cleaning blade and the imaging member of an electrostatographic reproduction machine. The noise-free silencer assembly includes (i) at least a partially compressed high density polymeric open cell foam inserted into a portion of an interior cavity of a C-shaped cross-section member, and (ii) a C-shaped cross-section member having longitudinal axis, a wall defining an interior cavity for containing the at least a partially compressed high density polymeric open cell foam, and a slot formed in the wall extending generally longitudinally and at an angle to the longitudinal axis of the C-shaped cross-section member for reducing self-vibration noises and screeching noises between a cleaning blade and the imaging member of an electrostatographic reproduction machine.